A typical configuration for a cellular wireless system is first of all described.
Cellular wireless communication systems are comprised of communication areas called cells which are base stations {sometimes referred to as eNB (e-UTRA Node B)} that cover a particular communication area.
These base stations have different names such as macrocell base stations (MeNB), picocell base stations, and femtocell base stations (HeNB: Home eNB), according to the width, and function of their area. The cellular wireless base station having the largest area is called the macrocell base station which contains terminals (sometimes referred to as UE or User Equipment) within a range from a few hundred to a few thousand meters.
In communication links that couple the base station to the terminal in wireless communication systems, the interference power generated from the neighboring cell base station in the downlink and the interference power from the terminals belonging to the neighboring cell base station in the uplink are known to exert effects on the quality of the communication link. At the cell-edge which is the boundary of the area covered by a base station, the desired signal from that base station's own cell must compete with interference power generated from adjacent cells. This interference power causes the SINR (Signal to Interference and Noise Power Ratio) which is an index for expressing received power quality to deteriorate and appears as a drastic drop in communication speed. Lowering the interference from adjacent cells is therefore an essential element in improving the overall system in terms of channel capacity during wireless access.
Transmit power control at the terminal during the uplink operation during wireless access is also closely involved with interference control. This relation is described using FIG. 13. The terminal 13-A in the figure must transmit at high power to overcome the path loss generated between itself and the serving cell base station 11-A (base station to which terminal 13-A belongs) and attain the desired signal (solid line arrows in the figure) at the specified communication quality. However, the high power at which the terminal 13-A transmits arrives at the neighboring cell base station 11-B (broken line arrows in the figure) as interference power which is a large interference power at the terminal 13-B that is connected to the neighboring cell base station 11-B. Conversely, the power from the transmission by the terminal 13-B arrives at the base station 11-A as interference power in the same way and acts as interference power on the terminal 13-A connected to the base station 11-A.